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Hi, I want to make dynamic patterns on a 8x24 LED matrix, with fading effects on each individual LED. I know I can use TLC5940 to expand the PWM outputs of my arduino nano. But can I connect the LEDs in the column-row scanning configuration while still having these effects? I hope to save up the number of pins I have to use. Thanks

[Reply #1 on:]

Hi, I want to make dynamic patterns on a 8x24 LED matrix, with fading effects on each individual LED. I know I can use TLC5940 to expand the PWM outputs of my arduino nano. But can I connect the LEDs in the column-row scanning configuration while still having these effects? I hope to save up the number of pins I have to use. Thanks

It should be possible, yes. You'll probably have to scan 8x8 then 8x16, so 16 steps in total for the scan (ie. 8+8).

If you're using the TLC5940 library you'll have to add the code to switch the rows into the interrupt handler which generates the XLAT pulses.

(You'll see what that means when you dig into the library code...)

[Reply #2 on:]

The answer to this is yes.  You can do either column or row scanning depending on the type of matrix.  The TLC5940 can only drive the anodes so if the matrix is "Anode Row Cathode Column" you have to drive it row-wise with the TLC5940 and scan the columns with +5V.  If the matrix is "Anode Column Cathode Row" you have to drive it column-wise with the TLC5940 and scan the rows with +5V .  So you set the "channels" for the next row or column and move the current row or column +5V on to the next one, repeat at about 800Hz.  So there is no choice there, but it can drive either type of matrix.  Personally, I like row-scanning.  It makes scrolling text very easy.  Here are some people doing it: